There is a great article I found that has tons of quotes about superficial membership in the Church. Below is just one of many to enjoy.

Neal A. Maxwell (1926-2004) Quorum of the Twelve Apostles

From Men and Women of Christ: If we enlist and take the Savior’s yoke upon us we “shall find rest unto [our] souls” (Matthew 11:29). If we are only part-time soldiers, though, partially yoked, we experience quite the opposite: frustration, irritation, and the absence of His full grace and spiritual rest. In that case weaknesses persist and satisfactions are intermittent. . . Actually the partially yoked experience little spiritual satisfaction, because they are burdened by carrying the awful weight of the natural man — without any of the joys that come from progressing toward becoming “the man of Christ.” They have scarcely “[begun] to be enlightened” (Alma 32:34). The meek and fully yoked, on the other hand, find God’s reassuring grace and see their weakness yielding to strength (see Ether 12:27).

Strange as it seems, a few of the partially yoked, undeservedly wearing the colors of the kingdom, are just close enough to the prescribed path and process to be able to observe in others some of the visible costs of discipleship. Sobered by that observation, they want victory without battle and expect campaign ribbons merely for watching; but there is no witness until after the trial of their faith (see Ether 12:6).

These same Church members know just enough about the doctrines to converse superficially on them, but their scant knowledge about the deep doctrines is inadequate for deep discipleship (see 1 Corinthians 2:10). Thus uninformed about the deep doctrines, they make no deep change in their lives. They lack the faith to “give place” (Alma 32:27) consistently for real discipleship. Such members move out a few hundred yards from the entrance to the straight and narrow path and repose on the first little rise, thinking, “Well, this is all there is to it”; and they end up living far below their possibilities. While not as distant as those King Benjamin described “For how knoweth a man the master whom he has not served, and who is a stranger unto him, and is far from the thoughts and intents of his heart?” (Mosiah 5:13) — these people are not drawing closer either. (Men and Women of Christ [1991], pp. 2-3)

Source: http://emp.byui.edu/WightmanG/Bom_121/Class_Articles/Sprfcl_Mmbrship.htm

Craig